6.2 General Psychology: How can we measure sensation?

6.2 Describe how we can measure sensation


Measurement of Sensation

1. Absolute threshold in sensation

This is the weakest stimulus that any sensory system can detect; it is the smallest amount of physical energy that will produce a sensation. Our senses respond to quite low levels of stimulation for example out vision – we can see a candle thirty miles away on a clear, dark night or we can smell one drop of perfume in a three roomed house.


Dogs have a better sense of hearing and smell while hawks have a keener sense of sight. Some fish have taste buds all over their bodies. Human beings can only see a fraction of the light waves surrounding them. They cannot see ultra violet rays or infra red rays.

2. Differential threshold

Differential threshold is the amount of change in a physical stimulus necessary to produce a just noticeable difference in sensation. Here we are talking about the smallest change in stimulation that a person can detect. An example is a good cook tastes a dish, then adds salt to it, then tastes it again to measure the change. Our ability to detect differences in stimulus intensity depends on the magnitude of the initial stimulus, we easily detect even small changes in weak stimulus, but we require much larger changes before we notice differences in strong stimuli for example small adjustments in soft music will be noticed while it takes longer to notice small adjustments in loud music.




6.3 Discuss the factors which influence human perception

Factors which influence Human Perception

1. Halo Effect

This is the tendency of letting your impressions or judgement of an individual be influenced by ones general impression of him or her for example a good student can easily get extra marks in an assignment.

2. Socio-cultural factors

We tend to judge others by our standards for example perception of beauty varies from one part of the world to another. In European societies, extremely thin women are seen as beautiful while in West African societies, it is very fat women who are viewed as being very beautiful.

3. Context or frame of reference

This is a framework which serves as a reference against which the properties of a particular object are perceived. It can determine or distort out perception. For example, when one sees the following two lines, one can easily assume that the second figure in the first line is the letter “B” while the second figure in the second sentence is seen as the number “13”.


            12    B    14    15

            A      B     C     D


  1. Set

The predisposition to act in a certain way is tied up with past experience for example if someone treated us badly, the next time we see them, we might approach them with caution.


  1. Individual personal adjustments, needs and wants

There is a relationship between an individuals needs, wants and his perception for example some parents are poor in perceiving their children’s faults and a person in love perceives his or her lover differently.


  1. State of health

When an individual is sick, he or she may see things differently for example, if an individual is sick and has to do an exam on that day, he might find the exam more difficult than he would if he did the exam when he is not sick.


  1. Mental state

An individual’s mental state also affects perception for example when one is drunk, one may perceive a prostitute in a bar as a very beautiful woman and will want to go home with her but when he is sober, he will not want anything to do with the prostitute.


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